It is often desirable to manufacture a single component which has the hardness and frictional properties of a thermoplastic elastomeric material in one region and the hardness and frictional properties of another thermoplastic material in other regions. For example, the thermoplastic elastomeric material may provide functions such as a built in gasket, or soft grip for “non-slip” handling, or skid free standing plane, or a high friction top to a modular belt or conveyor chain. The harder thermoplastic material can provide structure or mechanical strength to the component. In one example application, a thermoplastic elastomer, such a styrenic block copolymer, is laminated to a hard resin. The laminate is advantageous since it has a good feel, shock absorption (cushionability) and damage-resistance because of the flexibility and elasticity of the layer of the thermoplastic elastomer and has shape-retaining and reinforcing ability because of the hard resin.
While composites of a thermoplastic elastomer and a hard resin often have advantageous properties, it may be difficult to create an acceptable bond between the thermoplastic elastomer and the hard resin. Often mechanical coupling methods must be employed in which the thermoplastic elastomer and the hard resin are formed to have engaging means capable of being coupled together. However, the formation of engaging means typically require molds with complicated structures for forming the engaging means. Alternatively, the thermoplastic elastomer and the hard resin are often bonded together with some other bonding means, such as adhesives. The use of adhesives is also undesirable because it requires complicated steps to prepare the two layers followed by bonding. As a result, poorly-bonded composites are often produced, and organic solvents in adhesives often are detrimental in the working environment.
What is needed therefore is a method and materials wherein a thermoplastic elastomeric material can be readily molded to another harder thermoplastic material such that an acceptable bond forms between the thermoplastic elastomer and the harder thermoplastic material.